1. Field of the Invention
The invention relates to a semiconductor sensor to detect dynamic amounts such as acceleration, pressure, and the like and, more particularly, to a semiconductor sensor of the electrostatic capacitance type of detect a change in electrostatic capacitance of a displacement portion which is deformed according to an acceleration or pressure.
2. Related Background Art
As a conventional semiconductor sensor, there is known a sensor having a structure in which a silicon wafer is worked into a diaphragm shape and a resistance layer is formed thereon. In such a type of sensor, a change in resistance of the resistance layer due to a deformation of the diaphragm is detected by using a Wheatstone bridge circuit.
On the other hand, according to the conventional pressure sensor of the electrostatic capacitance type, a change in electrostatic capacitance due to deformations of two metallic diaphragms is detected by an external circuit.
The conventional semiconductor sensor, however, still has many points to be improved with respect to the detecting sensitivity, stability, corrosion resistance, and the like.
The conventional pressure sensor of the electrostatic capacitance type still has many points to be improved with regard to the miniaturization, connection with an external circuit, and the like.
On the other hand, in association with the progress of information equipment, consumer equipment, and control units, a demand for sensors using semiconductors is increasing more and more increasing. Various kinds of sensors have been developed to measure light, electricity, magnetism, acoustic wave, chemistry, dynamics, and the like. However, in association with the remarkable advancement in the development of robots or the like, the development of sensors for detecting and controlling a dynamic amount and having an excellent performance is demanded. Moreover, miniaturization and realization of a hybrid structure of the acceleration sensor and pressure sensor are required due to progress of the micromechanics technique.